Ninjas (Shinobi) hold a prominent place in the popular imagination. The word conjures images of black-clad figures engaging in hand-to-hand combat. Ninjas, however, were spies whose primary purpose was espionage and sabotage.
Ninjas did not do Karate though they practiced several martial arts. Furthermore, Ninjas were active between 1336 and 1600 while Karate arrived in Japan in 1920.
While Ninjas avoided direct, physical fights, they were trained in martial arts. This article will explore the historical reality of Ninjas as spies and mercenaries in Feudal Japan.
What Kind of Martial Arts Did Ninjas Practice?
Ninjas practiced a variety of martial arts for different purposes. They used variations of jujutsu for hand-to-hand combat, kenjutsu for swordsmanship, and iai for sword-drawing.
Since there is very little reliable documentation from the Shinobi era, detailed accounts of Ninja training are rare. Shinobi were primarily spies. They prioritized stealth. Because physical fighting is antithetical to discretion, it is improbable that Ninjas would have developed their unique form of combat. It would not have served their purposes.
Instead, the Shinobi relied on the dominant martial arts methods of the time. These would look different from clan to clan. Jujutsu, for example, is a broad term describing a form of hand-to-hand combat. Each sect would modify it to their specific needs and strengths.
Today, Ninja martial arts are comprehensively called Ninjutsu. There is, now, a modern, universal school of ninja practices. Feudal Japan was far too fractured for unified Shinobi training. The jujutsu applied looked different from Ninja to Ninja and each clan had its own variations.
Additionally, Shinobi had different specified purposes. Occasionally, Ninjas had to catch and detain criminals. These Shinobi would perfect Hojojutsu, a martial art that uses rope to bind the hands.
Ninja also practiced a variety of martial arts utilizing weapons. They studied Sojutsu and Naginata-do, a martial art that uses spears. Shinobi practiced Bojutsu to perfect their bo staff skills. They also learned Kyudo, an archery-based martial art.
Who Did Ninjas Fight Against?
Since Ninjas were primarily spies, they did not universally fight against any one specific group. That said, Samurai often hired Shinobi to commit acts against Bushido-the Samurai code of warfare.
Ninjas were mercenaries while the Samurai adhered to a strict code of warfare conduct. Samurai could not break Bushido, but they could hire other people to do so. Shinobi were employed to do what Samurai could not. 
Ninjas fought through stealth and deception hence their combat was not on the battlefield. They adeptly blended into their surroundings. Shinobi would disguise themselves as farmers and servants; whatever it took to remain undetected.
Ninjas infiltrated thor opponents for three fundamental purposes; to gain intelligence, sabotage their marks, and perform assassinations.
Shinobi trained extensively in espionage. They focused on three major areas:
- Tori-no-Jutsu covered under-cover operations as well as sneaking into camps.
- Shikari-no-Jutsu taught sabotage and how to enter enemy camps after war erupted.
- Ongyo-Jutsu taught them escape and deception.
Once in the enemy camp, Shinobi gathered intelligence. They committed sabotage by planting misinformation.
The Bansenshukai – one of the few primary texts about Ninjutsu practices-offers instruction on how to sew internal discord. It suggests ways to use interpersonal relationships to turn people against each other. Samurai contracted Ninjas to assassinate their enemies as well.
Ninjas were hugely helpful to Samurai; they were also tremendously damaging.
Samurai had a love-hate relationship with Shinobi. Ninjas did what Samurai could not. Bushido did not bind them, and Samurai often used Shinobi to defeat other Samurai. This practice inevitably bred paranoia. Samurai understood that if they were hiring Ninjas, it was very likely their enemies were as well. Thus, Samurai hated and needed Shinobi in equal measure.
What Kinds of Weapons Did Ninjas Have?
Ninjas prioritized small, easily concealed weapons. Shinobi needed to blend into their surroundings hence their weapons often served dual purposes. They were fatal and easily disguised as authentic pieces of Shinobi disguise.
Ninjas avoided fights in general. And since they relied heavily on stealth and secrecy, bulky, obvious weapons would compromise their cover. The best weapons could pass as parts of Shinobi disguises.
Some of the weapons Ninjas used are:
A Ninja passing as a farmer would use a Kusarigama. The Kusarigama is a sickle with a weight attached by a chain. Shinobi used the weight as a projectile. Ninjas swung it to incapacitate an enemy or knock a weapon from their hands while the sickle completed the attack. Additionally, the Kusarigama was small enough to be concealed in a man’s robes.
Shinobi also wore Shuku, which were gloves with four spikes on the palm. They were plated and used like brass knuckles. Ninjas used the inside of the palm to facilitate climbing-the spikes pierced surfaces and let the Shinobi pull themselves up.
Ninjas used a collection of small, easily hidden weapons called tonki. Tonki was the throwing star, the most readily identifiable piece of Ninja iconography. They are, in reality, called Shuriken.
However, whether or not Ninjas used Shuriken as projectiles is a source of debate. Scholars suggest they were gripped between the fingers and used like brass knuckles.
Shuriken was, however, not used frequently. Still, they were a sure and immediate indicator that the carrier was a Shinobi, as they had no purpose beyond combat.
Caltrops were another critical piece of Tonki. These were spikes with four points. Shinobi would drop them on the road behind them when they thought enemies were following them. The individuals tailing them would step on the caltrops, stabbing themselves. Caltrops were a necessary tool for escapes and evasions.
Ninjas favored weapons that could pass as farm tools.  The Gotoku was a sharpened trivet. While farmers used them to lift hot objects, Ninjas used them to sweep the legs of their enemies. They also used the sharpened edges as Shuriken.
Shinobi used blow darts for distance attacks. These weapons allowed them to remain hidden while incapacitating their prey. The long tubes needed to shoot the darts would immediately arouse suspicion so Ninjas carried flutes instead. These were used to shoot the darts and caused no alarm.
Ninjas did not practice Karate. They did, however, utilize a wide variety of martial arts and weapons.